Alarms have been extensively described and shown in the art. Alarms may be electrically or mechanically actuated and employ sirens, bells or other warning devices such as the horn described in the U.S. Pat. No. 3,670,689 to Pappas.
Alarms serve a wide variety of purposes, such as registering flood conditions, illegal entries, etc. Portable alarms are particularly useful in areas where fixed alarms are difficult to install and may be conveniently applied to a multiple number of uses.